Parenting Plans are also an effective means of formalising an agreement reached before any court action. The Plans do not have any formal requirements but should be in writing, signed by the parents and dated.
If you think you will require your arrangements to be enforceable (by a court) or otherwise need recognition by some third party agency then you will require Court Orders.
Section 63B of the Family Law Act sets out a legislative frame work that parents should be aware of.